Heat exchanger



Sept. 10, 1935. I. H. J. KERR 2,013,658

HEAT EXCHANGER O riginal Filed Nov. 10, 1928 Fig? J 56 INVENTOR.

Howard J Kre/"P Patented Sept. 10, 1935 HEAT EXCHANGEB yHoward J. Kerr, Westfield, N. J., assigner to The Babcock & Wilcox Company, Bayonne, N. J., a corporation of New Jersey Original application November 10, 1928, Serial No.

318,351. Divided and this application December 8, 1930, Serial No. 500,743

2 Claims.

This invention relates to an improved tubular heat exchanger as a part of a heat exchange system wherein heat from burning fuel is 'transmitted to said exchanger which applies the heat 5 to a iiuid passing therethrough.

When tubular heat exchangers are used in the radiant heat zones of boiler furnaces their metal is subjected at times to such high temperatures that its destructive effect is too severe for any adequately longv life of the device. Yet, it is highly desirable to utilize the heat radiantly transmitted from the burning fuel. It is an object of this invention to solve this problem.

It is a further object of the invention to pre.-

sent a practicalradiant steam vsuperheater heat` exchanger of novel construction in respect to its tube protection. l y

Another object is to provide superheater tube protection consisting of aheat resisting shell portion applied in plastic -condition to the tubes and anchored thereto.

Other objects of the invention will appear as the accompanying description proceeds. The invention is described with reference to the accompanying drawing, in which:

Fig. 1 is a vertical section throughx a boiler furnace equippedwith a radiantly heated steam superheater having the illustrative heat exchanger incorporated therein.

31- Fig. 2 is a longitudinal view of a heat exchanger having helical projections extending into a nonmetallic protector of great thickness.

Fig. 3 is a transverse sectional view taken on line 3-3 of Fig. 2. y

35 I 'I'his application is a division of my application Ser. No. 318,351, filed Nov. 10, 1928.

Fig. 1 shows a boiler furnace having a com-- y bustion chamber I0 in which burning fuel is supplied through a burner I2. Along the inner face of the furnace walls i4 and I6 are the illustrative heat exchangers.

is transmitted directly to themand through them to a fluid passing through .their inner metallic tubes. Coal, used as fuel, results in the deposition of refractory slag in plastic condition, the

deposition being governed `by the fusion characteristics of the refractory, and the relative temperatures, of tubes and furnace. y

When the tubulan structure is sufiiciently low in temperature, the plastic refractory, or slag carried by the burning fuelwill deposit and collect until it covers the heat exchanger. Projections and cooler portions of the exchanger F startsuch collections. 5" The construction shown in Figs. 2 and 3 of the keep the refractory in place.

Heat from the burning fuel` drawing presents an inner metallic tube I8 having outwardly extending projections spaced apart. Between these projections are bodies of heat resisting material, or refractory material, placed'on the metallic tube, ,either while in plastic 5 condition, or previously formed. The metal projections serve as bonding or holding means to These metal projections also serve as heat conductors, while the refractory is relatively a heat insulator. By va- 10 4rying the average thickness of the refractory shell, or by varying Lthe superficial area of rthe v metal covered by the refractory shell, the heat conducting capacity of the tube is varied, and the temperature of the metal kept within safe limits. 15

In proportion as-the heat conducting capacity of the tube is reduced by this means, o'r the metal temperature, so will the externalA surface have a higher average temperature whether such surface is wholly refractory or partly refractory 20 and partly metaLand the furnace temperature l and Where necessary, the grooves between projections may be' formed undercut or dovetail shaped to further increase the anchorage of thev refractory. 30 In Fig. 2,-` the projections 24 are continuously helical; leaving corresponding helical grooves 22 between. The metal projection is screw-thread in type, and may have any sectional shape, square, triangular or rounded, and may be undercut on 35 one or both sides.

In Fig. 1 the metal tubes have their intermediate sections presented to the heat from the burning fuel in the combustion chamber I0. Their ends extend through the Wall I4 on one side of 40 the furnace where they are expanded into inlet and outlet headers 46 and148 respectively. At the other side of the furnace is a similar construction including headers 5U and 52. Above the combustion chamber'is shown'a section 54 of a 45 water tube steam boiler of standard construction having uptake headers 56 and downcomers` 5B. `Steam generated .in this boiler (shown only in part) maybe led to onev set of headers by conl nections not shown, and be superheated in the 50 tubes as it passes to the other set of headers.

Such an arrangement constitutes a radiantly heated superheater for the steam boiler,the furnace of which is the source of heat'for superheating. Such radiant heat is received by the `ence-to specific structures, but it is to be appleytubesat avery highff'rate, and is absorbed by the steam at a rate increasing with the iow of steam through the superheater, and so varies with the boiler load. There is a normal tendency. for a state of unbalance to occur when load changes' and when starting or stopping a boiler, and when the steam ow inside the tubes is relatively deilcient with reference to radiant heat received, the

meta.l .temperature tends to rise and if some prociated that it is not limited to all of their details.

It is of ascope commensurate with the scope of the sub-joined claims.

What I claim is:

1. In power steam apparatus; a combustion s chamber; means for burning fuelwithin the combustion chamber; and radiantly vheated wall structures comprising an 'inner part of a wall of the combustion chamber receiving radiant heat from the burning fuel ,for transfer to a fluid passing through the structure; said structure comprising tubular elements through which the fluid is passing; helically disposed extensions of the 'tubular elementsV4 extending radially outwardly thereof to afford anchors; and non-metallic heat resisting material of greater thermal resistance than the material of the tube held in place by said anchors and placed around` the tube while it is in plastic condition.

2. In power steam apparatus; a combustion chamber; means for burning fuel within the comv bustion chamber; and radiantly heated wall structures comprising an inner part of a wallof the combustion chamber receiving radiant heat from the burning fuel for transfer to a fluid passing through the structure; said structure comprising tubular elements through which the fluid is passing; helically disposed extensions of the tubular elements extending radially outwardly thereof to afford anchors; and nonmetallic heat resisting material of greater thermal resistance than the material of the tube held in place by said anchors and placed around the tube while it is in plastic condition, said extensions substantially constituting threads formed on the tubular ele l ments.

HOWARD J. KERR. 

